`NATURAL ACTS` OFFERS DELIGHTFUL NEW INSIGHTS

John HusarCHICAGO TRIBUNE

Consider this about the mosquito:

''When she drinks, she drinks deeply: The average blood meal amounts to 2 1/2 times the original weight of the insect. Picture Audrey Hepburn sitting down to a steak dinner, getting up from the table weighing 380 pounds; then, for that matter, flying away.

''In the Canadian Arctic, where species of the genus Aedes emerge in savage, sky-darkening swarms like nothing seen even in the Amazon, and work under pressure of time because of the short summer season, an unprotected human could be bitten 9,000 times per minute.

''At that rate a large man would lose half his total blood in two hours. Arctic hares and reindeer move to higher ground, or die. And sometimes solid mats of Aedes will continue sucking the cool blood from a carcass. . . .''

David Quammen goes on for another 1,900 words or so in a bizarre chapter in his compelling book, the best thing I`ve seen on the market this year about wildlife. It is called ''Natural Acts,'' subtitled ''A Sidelong View of Science and Nature'' (Nick Lyons Books, New York, $16.95), and will be lionized by anyone who has fallen under the spell of such revealing masters of outdoor insight as the late Aldo Leopold and Sigurd Olson. In other words, this guy is a great, great outdoors writer. And while I normally do not devote whole columns to promote single books, this is one that I want to tell you about.

Here is Quammen on the enthralling notion that at least one out of four animals on earth is a beetle:

''This is actually a conservative estimate, reflecting only the number of animal species that have been discovered and identified by science. Add up all the known species of mammals and birds and reptiles and amphibians, all the fish and crustaceans and protoplasmic tentacle-waving sea creatures, every brand of zooplankton that`s ever been given a name, every type of worm, every flea, every mite, every spider, also of course every insect on the current entomological roster, and the total comes to around 1 1/4 million known species of animal. Of that vast assemblage, one in four is a beetle.

''We`re talking about an order called Coleoptera, containing 300,000 officially described species. And new beetles are being discovered almost every time some scientist waves a net through a rain forest. (A Smithsonian entomologist named Terry Erwin believes, from his study of jungle canopy in Peru, that there might be as many as 12 million species of beetle.)''

Quammen flames on and on through arcane yet relevant subjects--about innocent bats and a government project to convert the little buggers into living bombs during World War II, about brilliant, playful, shamelessly hot-dogging crows who probably are too smart for their element, about the legendary exaggerations concerning the anaconda, about those incredible survival abilities of the cockroach.

Here he is on the ''troubled gaze'' of the octopus, a timid underwater creature with winkable, humanoid eyes that eerily stare back, now subject to a West Coast insanity called octopus wrestling:

''The biggest specimens of dofleini were smoked out of their caves with solutions of noxious chemicals and wrestled up onto land by divers working in teams, there to be weighed and measured and admired . . . Panic-stricken dofleini have been known to pin a man`s arms to his sides, pull off his face mask, yank out his mouthpiece. There have even been several instances when a big octopus pounced on the back of an unsupecting diver from a rock ledge overhead . . .

''(In other words) . . . octopi in the 200-pound range or larger, cowering in sea caves off the coast near Seattle and known for their high-strung susceptibility to nervous disorders, have been kidnapped and terrorized intermittently by strange visitors in black neoprene, these latter often armed with knives and spears. Consequently, it can be assumed that eyeballs human-like but the size of grapefruit now gaze out from those caves, furtively, trepidatiously, some of them no doubt looking just a bit addled. Looking as though they might belong to animals that, like Pynchon`s beast, are in not quite the best mental health.

''My own view is this: Any giant octopus that grabs hold of a passing human probably has some pretty good reason. If not an unanswerable grievance, then at least a plausible insanity defense.

''Or maybe the creature is just desperate to communicate. Snatching that lone human up by the rubber lapels. Exigent as the Ancient Mariner. Transfixing the man or the woman with a big glittering eye. Listen. We know who you are. And we`ve seen what you do. But unfortunately the octopi, for all their intelligence, for all their sensitivity, for all their remarkable evolutionary sophistication, are born mute.''

Such convoluted, yet simple, scientific musings of this transplanted Midwesterner-cum-Montanan originally were generated in Quammen`s monthly column (called ''Natural Acts'') in Outside Magazine.

There, and here, he breathes importance into the little-known nitty-gritty of biology. He describes wondrous places, people and situations that range from the vitality of rivers to the awesome mysteries of cold. Here is Quammen introducing one of the most compelling subjects in natural science, and one with which we deal annually on Chicago`s Lakefront:

''Semelparity: An animal or a plant waits a very long time to breed only once, does so with suicidal strenuosity, and then promptly dies. The act of sexual procreation itself proves to be ecstatically fatal, fatally ecstatic. And the rest of us are left merely to say: Wow.

''. . . Bamboo do it. A group of hardy desert plants called the agave do it. Pacific salmon do it. The question is why. What can these three organisms, apparently so dissimilar, have in common? Why should all three--living in drastically different environments with drastically different life histories

--be similarly committed to dying for one taste of love?''

Naturally, Quammen offers some answers, some thrilling formulas that might have turned us into scientists when we were impressionably young. Unfortunately, none of my teachers held forth with such golden vitality, or if they did, my ears were closed.